Liquid crystal display apparatus having display panels on both upper and lower surfaces

ABSTRACT

A liquid crystal display apparatus includes a first liquid crystal display panel, a second liquid crystal display panel smaller in area than the first liquid crystal display panel. A flat backlight has an optical waveguide and a point light source placed near one side surface portion of the optical waveguide, and is placed between the first liquid crystal display panel and the second liquid crystal display panel. One reflecting layer is placed at least between the flat backlight and the second liquid crystal display panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2002-003122, filed Jan. 10,2002, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display apparatushaving display panels on both upper and lower surfaces.

2. Description of the Related Art

For example, as shown in FIG. 12, there is some cell phone designed suchthat a display portion housing 2 is pivotally attached to an operationkey portion housing 1 through a shaft 3. In this case, a key operationportion 4 is formed in the area enclosed with chain lines on theopposite surface of the operation key portion housing 1 to the displayportion housing 2. A liquid crystal display apparatus 5 is housed inalmost the central portion inside the display portion housing 2.

The display surface of a main liquid crystal display panel 6 is exposedon the opposite surface side of the liquid crystal display apparatus tothe operation key portion housing 1. As shown in FIG. 13, when thedisplay portion housing 2 is closed with respect to the operation keyportion housing 1, the display surface of a sub liquid crystal displaypanel 7 smaller in area than the main liquid crystal display panel 6 isexposed on the opposite side to the opposite side of the display portionhousing 2 to the operation key portion housing 1.

As described above, there is some cell phone having the liquid crystaldisplay panels 6 and 7 mounted on the two surfaces of the displayportion housing 2 pivotally attached to the operation key portionhousing 1 through the shaft 3. The sub liquid crystal display panel 7 isused to display the date/time, received contents, the telephone numberof the sender, or the like while the display portion housing 2 is closedwith respect to the operation key portion housing 1.

FIG. 14 is a sectional view of part of a conventional liquid crystaldisplay apparatus incorporated in such a cell phone. In this liquidcrystal display apparatus, the main liquid crystal display panel 6 andsub liquid crystal display panel 7 are placed to oppose each other at apredetermined distance, a main backlight 8 is placed on the oppositeside of the main liquid crystal display panel 6 to the display surfaceside, and a sub backlight 9 is placed on the opposite side of the subliquid crystal display panel 7 to the display surface side.

The backlights 8 and 9 are of an edge light type. Although not shown indetail, reflectors 12 and 13 are bonded on the opposite sides of thesebacklights to the opposite sides to the liquid crystal display panels 6and 7 to which optical waveguides 10 and 11 correspond, and a lightsource (not shown) such as a fluorescent tube or light-emitting diode isplaced near one end face of each of the optical waveguides 10 and 11.

The light emitted from each light source is incident on one end face ofeach of the optical waveguides 10 and 11. The respective incident lightbeams are reflected by the reflectors 12 and 13 and two-dimensionallyemerge from the opposite surfaces of the optical waveguides 10 and 11 tothe liquid crystal display panels 6 and 7. These emerging light beamsare incident on the liquid crystal display panels 6 and 7, and imagelight beams corresponding to the driving operations of the liquidcrystal display panels 6 and 7 emerge from the display surface sides ofthe liquid crystal display panels 6 and 7.

In the conventional liquid crystal display apparatus, since thededicated backlights 8 and 9 are respectively arranged for the liquidcrystal display panels 6 and 7, a large number of components arerequired, and the thickness of the overall apparatus is large. Thisleads to an increase in the thickness of the display portion housing 2of the cell phone.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a liquid crystaldisplay apparatus which can decrease the number of components and thethickness of the overall apparatus.

According to an aspect of the present invention, there is provided aliquid crystal display apparatus comprising a first liquid crystaldisplay panel, a second liquid crystal display panel smaller in areathan the first liquid crystal display panel, a flat backlight which hasan optical waveguide and a point light source placed near one sidesurface portion of the optical waveguide, and is placed between thefirst liquid crystal display panel and the second liquid crystal displaypanel, and one reflecting layer which is placed at least between theflat backlight and the second liquid crystal display panel.

According to this apparatus, since liquid crystal display panels areplaced on the two surfaces of one optical waveguide, the number ofcomponents can be decreased, and the thickness of the overall apparatuscan be reduced.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings; which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a plan view of a liquid crystal display apparatus according toan embodiment of the present invention;

FIG. 2 is a bottom view of the liquid crystal display apparatus in FIG.1;

FIG. 3 is a sectional view taken along a line III-III in FIG. 1;

FIG. 4 is a plan view of the apparatus in FIG. 1 from which a main caseis removed;

FIG. 5 is a bottom view of the apparatus in FIG. 2 from which the maincase, sub case, and sub liquid crystal display panel are removed;

FIG. 6 is a bottom view of the apparatus in FIG. 5 from which the mainflexible wiring board is removed;

FIG. 7 is an enlarged sectional view of part of the first example of atranslucent reflector;

FIG. 8 is an enlarged sectional view of part of the second example of atranslucent reflector;

FIG. 9 is an enlarged sectional view of part of the third example of atranslucent reflector;

FIG. 10A is an enlarged plan view of an example of a portioncorresponding to one pixel without any dedicated reflector;

FIG. 10B is an enlarged sectional view taken along a line X_(B)-X_(B) inFIG. 10A;

FIG. 11A is an enlarged sectional view of another example of a portioncorresponding to one pixel without any dedicated reflector;

FIG. 11B is an enlarged sectional view taken along a line XI_(B)-XI_(B)in FIG. 11A;

FIG. 12 is a perspective view of an example of a conventional cellphone;

FIG. 13 is a perspective view showing the display portion housing of thecell phone in FIG. 12 in a closed state; and

FIG. 14 is a sectional view of part of an example of a conventionalliquid crystal display apparatus incorporated in the cell phone shown inFIGS. 12 and 13.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a plan view of a liquid crystal display apparatus according toan embodiment of the present invention. FIG. 2 is a bottom view of theapparatus. FIG. 3 is a sectional view taken along a line III-III inFIG. 1. This liquid crystal display apparatus is housed in a displayportion housing 2 in FIG. 12 and includes an intermediate case 21, maincase 22, and sub case 23.

The intermediate case 21 is made of a resin and has four strip portions25 (see FIGS. 4 and 6; note that the convex strip portion 25 on theupper side is formed wider to a certain extent than the convex stripportions 25 on the remaining sides in FIGS. 4 and 6) which areintegrally connected in the form of a ring protruding inward and locatedslightly above the middle portion in FIG. 3 in the direction of heightof a rectangular frame-like portion 24. A main liquid crystal displaypanel housing portion 26 is formed on one side of these convex stripportions 25, and a backlight housing portion 27 is formed on the otherside. Engaging projection portions 28 (see FIG. 6) are formed at aplurality of predetermined portions of the outer surfaces of the twolong side portions of the frame-like portion 24, and a notched portion29 (see FIG. 6) is formed in a predetermined portion of the outersurface of the upper short side portion of the frame-like portion 24.

The main case 22 is formed from a metal plate and has six side wallportions 33 (one on the upper and lower sides each, and two on the leftand right sides each), each corresponding to one of the engagingprojection portions 28 of the intermediate case 21, on the four sideportions of an almost rectangular frame-like portion 32 having arectangular opening 31. Each side wall portion 33 of the main case 22extends in the vertical direction on the drawing surface of FIG. 1, andan engaging hole 34 formed in the extended portion at the middleposition thereof is engaged with the corresponding engaging projectionportion 28 formed on the intermediate case 21, thus the main case 22 ismounted on the main liquid crystal display panel housing portion 26 ofthe intermediate case 21.

The sub case 23 is formed from a metal plate smaller than the main case22 and has four side wall portions 37 (two on the left and right sideseach), each corresponding to one of the engaging projection portions 28of the intermediate case 21, formed on the two short side portions of arectangular frame-like portion 36 having a rectangular opening 35. Inthis case, the size of the opening 35 of the sub case 23 is smaller to acertain extent than that of the opening 31 of the main case 22. Eachside wall portion 37 of the sub case 23 extends in the verticaldirection on the drawing surface of FIG. 1, and an engaging hole 38formed in the extended portion at the middle position is engaged withthe predetermined engaging projection portion 28 of the intermediatecase 21, thus the sub case 23 is mounted on the backlight housingportion 27 of the intermediate case 21.

A main liquid crystal display panel 41 is housed in the main liquidcrystal display panel housing portion 26 of the intermediate case 21.The main liquid crystal display panel 41 is formed by bonding twotransparent substrates 42 and 43, each made of a glass material or thelike, through an almost rectangular frame-like seal member (not shown),sealing a liquid crystal (not shown) between the two transparentsubstrates 42 and 43 inside the seal member, and respectively attachedwith polarizing plates 44 and 45 on the outer surfaces of the twotransparent substrates 42 and 43.

The peripheral portion of the outer surface of the transparent substrate43 on the opposite side to the display surface side of the main liquidcrystal display panel 41 is supported with the convex strip portions 25of the intermediate case 21. The polarizing plate 44 on the displaysurface side is placed inside the opening 31 of the main case 22. Theperipheral portion of the outer surface of the transparent substrate 42on the display surface side is pressed against the inner surface of themain case 22 at the outer peripheral portion of the opening 31. In thisstate, the main liquid crystal display panel 41 is housed in the mainliquid crystal display panel housing portion 26 of the intermediate case21.

A flat backlight 51 is housed in the backlight housing portion 27 of theintermediate case 21. The backlight 51, which will be described indetail later, includes an almost rectangular optical waveguide 52corresponding in size to the main liquid crystal display panel 41, and areflector 53 bonded to a predetermined surface (the lower surface inFIG. 3) of the optical waveguide 52.

The backlight 51 is housed in the backlight housing portion 27 while theperipheral portion of the other surface of the optical waveguide 52 isin contact with the convex strip portions 25 of the intermediate case21. In this case, although described in detail later, a main flexiblewiring board 72 and backlight flexible wiring board 57 are arrangedbetween the reflector 53 and the sub case 23.

A sub liquid crystal display panel 61 is placed on the outer side (lowerside in FIG. 3) of the opening 35 of the sub case 23 so as to cover theopening. The sub liquid crystal display panel 61 is formed by bondingtwo transparent substrates 62 and 63 through an almost rectangularframe-like seal member (not shown), sealing a liquid crystal (not shown)between the two transparent substrates 62 and 63 inside the seal member,and respectively attached with polarizing plates 64 and 65 on the outersurfaces of the two transparent substrates 62 and 63. In this case, thesize of the sub liquid crystal display panel 61 is smaller to a certainextent than that of the main liquid crystal display panel 41. A colorsheet 66, e.g., a blue sheet, is attached to the outer surface of thepolarizing plate 65 on the opposite side to the display surface side.

The polarizing plate 65 and the color sheet 66 attached on the outersurface of the polarizing plate 65 are arranged in the opening 35 of thesub case 23. In this state, the peripheral portion defining the outersurface of the transparent substrate 63 on the opposite side to thedisplay surface side is bonded to the outer surface of the outerperipheral portion defining the opening 35 of the sub case 23. In thismanner, the sub liquid crystal display panel 61 is placed outside theopening 35 of the sub case 23.

FIG. 4 is a plan view of the apparatus in FIG. 1 from which the maincase 22 is removed. The size of a long side of the transparent substrate43 on the opposite side to the display surface side of the main liquidcrystal display panel 41 is larger than that of the transparentsubstrate 42 on the display surface side, and the upper side portion ofthe transparent substrate 43 in FIG. 4 protrudes from the transparentsubstrate 42 to form a protruding portion 43a. One semiconductor chip 71constituted by an LSI for driving the main liquid crystal panel and thelike is mounted on the almost middle portion of the protruding portion43a on the display surface side.

One end portion of the main flexible wiring board 72 is joined to theprotruding end portion of the protruding portion 43a on the displaysurface side. The main flexible wiring board 72 is bent through almost180° near one end portion, and a lower portion of main flexible wiringboard 72 is placed between the reflector 53 of the backlight 51 and thesub case 23 through the notched portion 29 of the intermediate case 21,as shown in FIG. 3.

FIG. 5 is a bottom view of the state shown in FIG. 2 from which the maincase 22, sub case 23, and sub liquid crystal display panel 61 areremoved. The main flexible wiring board 72 has a double-sided wiringstructure and includes a lower portion or base film 73 slightly largerthan the reflector 53 of the backlight 51. A rectangular opening 74 isformed in a predetermined portion of the base film 73. This opening 74is smaller than the outer size of the sub liquid crystal display panel61 but is slightly larger than the area of the two polarizing plates 64and 65, i.e., the display area of the sub liquid crystal display panel61.

The opening 74 of the main flexible wiring board 72 is located at aposition corresponding to the two polarizing plates 64 and 65 of the subliquid crystal display panel 61. In this case, since the base film 73 ofthe main flexible wiring board 72 is placed between the sub liquidcrystal display panel 61 and the reflector 53 of the backlight 51, aportion of the reflector 53 which does not correspond to the polarizingplate 65 of the sub liquid crystal display panel 61 is covered with aportion of the main flexible wiring board 72 other than the opening 74.

Referring to FIG. 5, a sub connector 75 and backlight connector 76 aremounted on the upper surface (the opposite surface to the sub liquidcrystal display panel 61 as shown in FIG. 2) of the base film 73, andchip components (not shown) such as capacitors and resistors are mountedon other predetermined portions.

As shown in FIG. 2, the size of a long side of the transparent substrate63 on the opposite side to the display surface side of the sub liquidcrystal display panel 61 is larger than that of the transparentsubstrate 62 on the display surface side, and the lower side portion ofthe transparent substrate 63 protrudes from the transparent substrate 62on the display surface side to form a protruding portion 63a. Asemiconductor chip 77 constituted by an LSI for driving the sub liquidcrystal display panel and the like is mounted on the display surfaceside of this protruding portion 63a. One end portion of a sub flexiblewiring board 78 is joined to the protruding end portion of theprotruding portion 63a on the display surface side. The other endportion of the sub flexible wiring board 78 is inserted into the subconnector 75.

FIG. 6 is a bottom view of the state shown in FIG. 5 from which the mainflexible wiring board 72 is removed. The backlight 51 includes theoptical waveguide 52, reflector 53, light-emitting diode (point lightsource) 54, and backlight flexible wiring board 57. The opticalwaveguide 52 is made of a transparent resin such as acrylic resin andformed into an almost rectangular plate-like shape having an outer sizethat makes the optical waveguide be tightly housed in the backlighthousing portion 27 of the intermediate case 21. An opening 52a is formedin one corner portion of the optical waveguide 52. The reflector 53 hasone side 53a and is smaller in outer size than the optical waveguide 52.The reflector 53 is bonded on one surface of the optical waveguide 52.The opening 52a of the optical waveguide 52 is located outside one side53a of the reflector 53, and the light-emitting diode 54 is embedded inthe opening 52a.

The light-emitting diode 54 is placed such that the normal to thelight-emitting surface, i.e., an optical axis 54a, is slightly shiftedtoward a long side of the optical waveguide 52 near the light-emittingdiode 54 with respect to a diagonal line connecting one corner portionof the reflector 53 and a corner portion on the opposite side. That is,the light-emitting diode 54 is located slightly inside from a cornerportion of the transparent substrate 42 on the display surface side ofthe main liquid crystal display panel 41. This makes it possible toreduce the width of the liquid crystal display apparatus. The upper sideend (on the side where the light-emitting diode 54 is placed) of theoptical waveguide 52 has a notched portion 55 forming an inclinedsurface 55a that gradually separates from the short side of the opticalwaveguide 52 with an increase in distance from the light-emitting diode54. Since light emitted from the light-emitting diode 54 is partlyreflected by the inclined surface 55a and incident on the opticalwaveguide 52, an increase in brightness can be attained as a whole.Almost the entire portion of the intermediate case 21 is formed into aframe-like shape, and a portion corresponding to the notched portion 55of the optical waveguide 52, i.e., an inside surface 25a of the stripportions 25, is located inward from the deepest portion of the notchedportion 55 to cover the entire notched portion 55 of the opticalwaveguide 52. This prevents the light emitted from the light-emittingdiode 54 from leaking outside the main liquid crystal display panel 41.

At a predetermined corner portion of the optical waveguide 52, one endportion of the backlight flexible wiring board 57 having an almoststrip-like shape is connected and joined to the light-emitting diode 54.As shown in FIG. 5, the backlight flexible wiring board 57 is placed onthe outer surface side of the main flexible wiring board 72, and theother end portion of the backlight flexible wiring board 57 is insertedinto the backlight connector 76.

In this liquid crystal display apparatus, when the main liquid crystaldisplay panel 41 is to be used, the light-emitting diode 54 is turnedon, and the light emitted from the light-emitting diode 54 is incidenton the optical waveguide 52 through the inner surface of the opening 52aformed in one corner portion of the optical waveguide 52. This incidentlight is reflected by the reflector 53 and two-dimensionally emergesfrom the opposite surface of the optical waveguide 52 to the main liquidcrystal display panel 41. The main liquid crystal display panel 41 isirradiated with this emerging light, and image light corresponding tothe driving operation of the main liquid crystal display panel 41emerges from the display surface side of the main liquid crystal displaypanel 41.

When the sub liquid crystal display panel 61 is to be used, thelight-emitting diode 54 is turned off, and external light is used. Thatis, external light is transmitted through the sub liquid crystal displaypanel 61, the color sheet 66, and the opening 74 of the main flexiblewiring board 72 and then reflected by the reflector 53. The reflectedlight is transmitted through the opening 74 of the main flexible wiringboard 72 and the color sheet 66. The sub liquid crystal display panel 61is irradiated with the transmitted light, and image light correspondingto the driving operation of the sub liquid crystal display panel 61emerges from the display surface side of the sub liquid crystal displaypanel 61. In this case, the image light emerging from the displaysurface side of the sub liquid crystal display panel 61 has a color(e.g., blue) corresponding to the color sheet 66.

In this manner, in this liquid crystal display apparatus, the liquidcrystal display panels 41 and 61 are placed on the opposite surfacesides of the optical waveguide 52 having the reflector 53 mounted on thepredetermined surface, and the main liquid crystal display panel 41 isused as a transmission type panel, while the sub liquid crystal displaypanel 61 is used as a reflection type panel. This allows only onebacklight 51 to be placed between both liquid crystal display panels 41and 61. This makes it possible to decrease the number of components andthickness of the overall apparatus. As a consequence, when this liquidcrystal display apparatus is incorporated in a cell phone like the oneshown in FIGS. 12 and 13, a reduction in the thickness of the displayportion housing 2 can be attained.

In addition, in this liquid crystal display apparatus, the main flexiblewiring board 72 is placed between the sub liquid crystal display panel61 and the reflector 53, and the portion of the reflector 53 which doesnot correspond to the polarizing plate 65 of the sub liquid crystaldisplay panel 61 is covered with the portion of the main flexible wiringboard 72 other than the opening 74. Even if, therefore, external lightenters through the opening 35 of the sub case 23 around the polarizingplate 65 of the sub liquid crystal display panel 61, this external lightcan be absorbed by the main flexible wiring board 72. The main flexiblewiring board 72 can therefore be made to have the function of alight-shielding film. This makes it possible to reliably preventunnecessary light leakage through the opening 35 of the sub case 23around the polarizing plate 65 of the sub liquid crystal display panel61.

The above embodiment has exemplified the case wherein a total reflectiontype reflector is used as the reflector 53. If, however, a translucentreflector is used as the reflector 53, the sub liquid crystal displaypanel 61 can be used as both a transmission type and a reflection type.

Assume that the reflector denoted by reference numeral 53 in FIG. 3serves as a translucent reflector. In this case, while thelight-emitting diode 54 is OFF, external light from the display surfaceside of the sub liquid crystal display panel 61 is transmitted throughthe sub liquid crystal display panel 61 and color sheet 66 and partlyreflected by the reflector 53. This light is then transmitted throughthe color sheet 66 again and emerges to the display surface side of thesub liquid crystal display panel 61, thereby realizing reflection typedisplay of a color (e.g., blue) corresponding to the color sheet 66.

While the light-emitting diode 54 is ON, the light emitted from thelight-emitting diode 54 is incident through the inner surface of theopening 52a of the optical waveguide 52, travels in the opticalwaveguide 52, and is transmitted through the reflector 53. Thistransmitted light is transmitted through the opening 74 of the mainflexible wiring board 72 and the color sheet 66. The sub liquid crystaldisplay panel 61 is irradiated with this transmitted light, and imagelight corresponding to the driving operation of the sub liquid crystaldisplay panel 61 emerges from the display surface side of the sub liquidcrystal display panel 61. As a consequence, the sub liquid crystaldisplay panel 61 performs transmission type display. In this case aswell, the image light emerging from the display surface side of the subliquid crystal display panel 61 has a color corresponding to the colorsheet 66.

When the main liquid crystal display panel 41 is to be used, the lightemitted from the light-emitting diode 54 is incident through the innersurface of the opening 52a of the optical waveguide 52, travels in theoptical waveguide 52, and is partly reflected by the translucentreflector 53. This light then emerges to the main liquid crystal displaypanel 41 side. When the main liquid crystal display panel 41 is used,reflection type display can be performed. However, external light fromthe display surface side of the main liquid crystal display panel 41travels in the direction of thickness of the optical waveguide 52, ispartly reflected by the reflector 53, and emerges to the display surfaceside of the main liquid crystal display panel 41. In this case, since ashade corresponding to the thickness of the optical waveguide 52 is caston a display image, the thickness of the waveguide 52 is preferablyminimized.

The optical waveguide 52 and translucent reflector 53 are almost equalin size to the main liquid crystal display panel 41 and larger than thesub liquid crystal display panel 61. For this reason, light is alsotransmitted through the translucent reflector 53 even at a positionaround the polarizing plate 65 of the sub liquid crystal display panel61.

As described above, however, since the main flexible wiring board 72 isplaced between the sub liquid crystal display panel 61 and the reflector53, and the portion of the reflector 53 which does not correspond to thesub liquid crystal display panel 61 is covered with the portion of themain flexible wiring board 72 other than the opening 74, even if lightis transmitted through the reflector 53 at a position around thepolarizing plate 65 of the sub liquid crystal display panel 61, thetransmitted light can be absorbed by the main flexible wiring board 72.In this case as well, therefore, the main flexible wiring board 72 canbe made to have the function of a light-shielding film. This makes itpossible to reliably prevent unnecessary light leakage through theopening 35 of the sub case 23 around the polarizing plate 65 of the subliquid crystal display panel 61.

As a translucent reflector, as shown in FIG. 7, a plate obtained bydispersing reflecting particles 82 in a transparent resin plate 81 maybe used. Alternatively, as shown in FIG. 8, a plate obtained by formingone reflecting layer 85 made of aluminum, silver, or the like on onesurface of a transparent resin plate 83 in correspondence with one pixel84 indicated by chain lines may be used. In this case, the area of thereflecting layer 85 is 30 to 70% of the area of one pixel 84.Alternatively, as shown in FIG. 9, a plate obtained by forming aplurality of dotted reflecting layers 88 made of aluminum, silver, orthe like on one surface of a transparent resin plate 86 for one pixel 87indicated by a chain line may be used. In this case, the total area ofthe plurality of reflecting layers 88 is 30 to 70% of the area of onepixel 87. Furthermore, translucent reflectors may be placed on theopposite surfaces of the optical waveguide 52. In this case, reflectiontype display and transmission type display can be done on both the mainliquid crystal display panel and the sub liquid crystal display panelunder almost the same conditions.

Instead of a dedicated reflector, a reflecting layer made of aluminum,silver, or the like may be formed on one surface of the opticalwaveguide 52 by vapor deposition, sputtering, or the like.Alternatively, instead of a dedicated translucent reflector, one or aplurality of dotted reflecting layers may be formed on one or twosurfaces of the optical waveguide 52 with respect to one pixel byproperly patterning a reflecting layer made of aluminum, silver, or thelike formed by vapor deposition, sputtering, or the like.

In addition, only the optical waveguide 52 may be placed between themain liquid crystal display panel 41 and the sub liquid crystal displaypanel 61. In this case, however, both liquid crystal display panels 41and 61 are of an active matrix type, with one pixel being constituted bya transmitting portion and reflecting portion.

For example, as shown in FIGS. 10A and 10B, a reflecting layer 92 madeof aluminum, silver, or the like is formed on the upper surface (theopposite surface to the transparent substrates 42 and 62 in FIG. 3) of atransparent substrate 91 corresponding to the transparent substrates 43and 63 in FIG. 3. An insulating film 93 is formed on the entire uppersurface, and a pixel electrode 94 made of ITO is formed on the uppersurface of the insulating film 93. In this case, the area of thereflecting layer 92 is 30 to 70% of the area of the pixel electrode 94.In one pixel, the reflecting layer 92 forms a reflecting portion, and aportion of the pixel electrode 94 which does not overlap with thereflecting layer 92 forms a transmitting portion.

Alternatively, as shown in FIGS. 11A and 11B, a plurality of dottedreflecting layers 92a may be formed for one pixel electrode 94. In thiscase, the total area of the plurality of reflecting layers 92a is 30 to70% of the area of the pixel electrode 94. In one pixel, the pluralityof reflecting layers 92a form reflecting portions, and a portion of thepixel electrode 94 which does not overlap with the reflecting layers 92aform transmitting portions.

In the arrangement shown in FIGS. 10A and 10B or 11A and 11B, only oneoptical waveguide 52 is placed between the main liquid crystal displaypanel 41 and the sub liquid crystal display panel 61, and hence areflector or translucent reflector becomes unnecessary. The number ofcomponents can be reduced accordingly, and the thickness of the overallapparatus can be reduced.

In addition, the above embodiment has exemplified the structure in whichthe point light source formed from a light-emitting diode is embedded inthe optical waveguide. However, an inclined surface (serving as a lightincident surface) may be formed to extend across two sides adjacent to acorner portion (one or a plurality of portions) of the opticalwaveguide, and a point light source may be placed near the inclinedsurface. The above embodiment has exemplified the case wherein the pointlight source formed from a light-emitting diode is used. However, thepresent invention is not limited to this, and a line light source suchas a fluorescent lamp may be used. In this case, the line light sourcemay be placed near one side of the optical waveguide. In addition, theabove embodiment has exemplified the case wherein the backlight havingthe optical waveguide is used as a flat backlight. However, the presentinvention is not limited to this, and a flat light-emitting device suchas an EL (electroluminescence) panel may be used.

As has been described above, according to the present invention, sincethe liquid crystal display panels are placed on the two surface sides ofone optical waveguide, the number of components can be reduced, and thethickness of the overall apparatus can be reduced.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A liquid crystal display apparatus comprising: a first liquid crystaldisplay panel; a second liquid crystal display panel smaller in displayarea than the first liquid crystal display panel; a flat backlight whichhas an optical waveguide and a point light source placed near one sidesurface portion of the optical waveguide, and is placed between andilluminates the first liquid crystal display panel and the second liquidcrystal display panel; and one reflecting layer which is placed at leastbetween the flat backlight and the second liquid crystal display panel;and a flexible wiring board disposed between said second liquid crystaldisplay panel and said one reflecting layer, said flexible wiring boardbeing connected to said first liquid crystal display panel and having anopening corresponding to said display area of said second liquid crystaldisplay panel.
 2. An apparatus according to claim 1, wherein thereflecting layer includes a total reflection type reflecting layer. 3.An apparatus according to claim 1, wherein the reflecting layer includesa translucent reflecting layer.
 4. An apparatus according to claim 3,wherein the translucent reflecting layer includes a transparent resinand a reflecting member.
 5. An apparatus according to claim 4, whereinan area of the reflecting member included in the translucent reflectinglayer is 30 to 70% of an area of one pixel.
 6. An apparatus according toclaim 1, wherein a size of the optical waveguide is substantially equalto a size of the first liquid crystal display panel.
 7. An apparatusaccording to claim 1, which further comprises a wherein the flexiblewiring board is connected to the first and second liquid crystal displaypanels, and placed between the reflecting layer and the second liquidcrystal display panel.
 8. An apparatus according to claim 7 1, whereinsaid opening of the flexible wiring board has an opening correspondingto coincides with said display area of the second liquid crystal displaypanel.
 9. An apparatus according to claim 8, wherein a size of theopening of the flexible wiring board is smaller larger than a size ofthe display area of the second liquid crystal display panel and issmaller than a size of a display area of the first liquid crystaldisplay panel.
 10. An apparatus according to claim 1, wherein theoptical waveguide has a substantially rectangular shape, and the pointlight source is placed on a short-side side near one corner portion ofthe optical waveguide.
 11. An apparatus according to claim 10, whereinthe point light source is placed such that an optical axis thereof isslightly shifted toward a long side of the optical waveguide near thepoint light source with respect to diagonal line connecting one cornerportion of the optical waveguide and a corner portion on an oppositeside thereto.
 12. An apparatus according to claim 10, wherein a shortside portion of the optical waveguide near the point light source has anotched portion forming an inclined surface that gradually separatesfrom a short side with distance from the point light source.
 13. Anapparatus according to claim 1, wherein the optical waveguide has anopening, and the point light source is placed inside the opening.
 14. Anapparatus according to claim 1, which further comprises a backlightflexible wiring board connected to the point light source, and placedbetween the reflecting layer and the second liquid crystal displaypanel.
 15. An apparatus according to claim 1, further comprising a case,the case having a liquid crystal display panel housing portion whichhouses the first liquid crystal display panel and a backlight housingportion which houses the backlight.
 16. An apparatus according to claim15, wherein the case has an intermediate case having the liquid crystaldisplay panel housing portion and the backlight housing portion, and apair of metal plate cases placed on upper and lower surfaces of theintermediate case.
 17. An apparatus according to claim 16, wherein oneof the metal plate cases has an opening corresponding to the secondliquid crystal display panel.
 18. An apparatus according to claim 17,wherein the second liquid crystal display panel is placed outside one ofthe metal plate cases.
 19. A liquid crystal display apparatuscomprising: a first liquid crystal display panel; a second liquidcrystal display panel smaller in area than the first liquid crystaldisplay panel; a flat backlight placed between the first liquid crystaldisplay panel and the second liquid crystal display panel; and atranslucent reflecting layer placed between the flat backlight and thesecond liquid crystal display panel.
 20. An apparatus according to claim19, wherein the flat backlight includes an optical waveguide, and thetranslucent reflecting layer is formed on the optical waveguide.
 21. Aliquid crystal display apparatus comprising: a first liquid crystaldisplay panel; a second liquid crystal display panel smaller in areathan the first liquid crystal display panel; and a flat backlight whichhas an optical waveguide and a point light source placed near one sidesurface portion of the optical waveguide, and is placed between thefirst liquid crystal display panel and the second liquid crystal displaypanel, wherein the first liquid crystal display panel has a translucentreflecting layer including a reflecting layer and a transparent pixelelectrode, and the second liquid crystal display panel has a translucentreflecting layer including a reflecting layer and a transparent pixelelectrode.
 22. An apparatus according to claim 21, wherein an area of atleast one of the reflecting layers is 30 to 70% of an area of thetransparent pixel electrode.